Re: Sigtran Digest, Vol 46, Issue 5

Li,

Why refuse to use the facility that was specifically placed in the RFC to
provide for independent user parts?

That facility is the DPC/SI RK.  If you refuse to use it, do not expect
to benefit from the fuctionality it provides.  Too hard and too complex:
not!  M3UA is the "interface" between MTP and an MTP-User.  It is not even
a stack: it is a shim.  SS7 stacks do this all day long.

Sending SG messages in the wrong direction from an ASP is simply not an
option.  DUPU and SCON corresponds to MTP-STATUS, DUNA to MTP-PAUSE and DAVA
MTP-RESUME.  These primitives go from MTP to MTP-User; *not* *visa* *versa*.
If an MTP User wishes to attach to or withdraw from the MTP/MTP-User interface
and an MTP-SAP it uses an implementation dependent local binding and unbinding
function.  For M3UA this is the ASP TM procedures and messages.  ASP Active/Ack
attaches to the MTP-SAP (PC/SI) and ASP Inactive/Ack detaches from the
MTP-SAP.  Local to the SS7 stack *at* *the* *SG*, an MTP-User detaching from
the MTP-SAP results in UPU(unavailable) being sent for the corresponding
MTP-SAP.  That's how SS7 works.  That's how M3UA works.

Be very clear: when you are using the ASP/SG configuration, the SG is simply
backhauling its local MTP/MTP-User interface to the ASP.

--brian

-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/